Juvenile Dermatomiositis (JD) is autoimmune disease that progresses with time; JD's main differentiated syndromes are rash on the skin, poor function of muscles, and often developing invalidism. If the health practitioners manage to diagnose the JD on an early stage and prescribe the adequate treatment the disease will not progress aggressively. This approach is tangible for practical rheumatology and pediatric. The article aims to present the reasons of the development of the JD and calcinosis. The study based on the description of the patients with JD. There are distinguished the main symptoms of the disease in children: frequent and acute developments of muscles calcinosis, occasionally with diffuse character followed with hypotrophy of the muscles, contractures and invalidism. One of the patient cases that describe the article is the thirteen-year boy with JD indicating repeated sequence of the disease, with diffusive calcinosis, cellulitis followed with secondary infection and impaired vision.